Non-metallic pipes are widely used for transporting low pressure gases. For example, Medium Density Poly-Ethylene (MDPE), High Density Poly-Ethylene (HDPE), and Aldyl-A pipes are used in natural gas distribution networks that transport natural gas from high pressure transmission pipelines to end users. The practice of nesting pipe inserts within previously installed lengths of “parent” or “host” pipeline is used as a lower cost alternative to removing and replacing existing distribution pipeline sections that have become unfit for service (e.g., because of aging or accidentally inflicted damage). Additionally, it is customary to fit a locator or tracer wire along the length of the parent pipe to facilitate locating the otherwise non-conductive pipe using a metal detector while the pipe is buried in the ground. Safely working on distribution pipeline requires a-priori knowledge of the presence or absence of such inserts, which must be gleaned without damaging the pipe or disrupting the flow of gas within. Existing approaches based on, for example, radiography or tapping into the line require expensive equipment, service disruptions, highly trained operators, and special safety precautions.